[mapserver-users] turning on layers at a particular zoom level

Bill Thoen bthoen at gisnet.com
Wed Sep 9 09:53:35 EDT 2009


sunny74 wrote:
> I am now loading the layers in groups instead of individually.
> First I am loading the base layer followed by 4 groups of layers, first
> group contains 2 while others contain 3 each.
>
> But the problem now is that at PageLoad for the first time the layers of
> group1 are not visible because it is getting overlapped by the other layers.
> The other layers are also not visible bec' they are mandated to be visible
> at higher zoomin levels because of max/min scaledom.
>
> Now if I load the group1 layers last then not only is it visible at initial
> zoom level but also at higher zoom levels bec' in that case it is
> overlapping the other layers mandated to be visible at that level.
>
> So how to tackle the problem.
>   
Tricky, isn't it?

Sometimes it helps to use different mapfiles for different zoom levels. 
There is a way to automatically switch to a different mapfile when the 
current one goes beyond its maximum or minimum scale, but I don't 
remember how to do that just now.  Hmm.... and I can't find it in the 
docs either. Probably because I forget what it's called. It was useful 
for even doing projection changes as the map became more local. I 
believe it's one of the MAX/MIN commands.

I also found that some effects that I wanted couldn't be done exactly 
the way I wanted, but there was always a way to reorganize and set 
things up to get what I needed.


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